I got the letter for the hilford secret lab, but nothing i do opens it, i wonder what else am i sopposed to do, also i m wondering how i can get all the animations i cant find, like the girls from the restaurant "delivery girls" , "short wendy" and the "tall wendy"

Hidden door. And how do you enter rooms in this game. Now check that near that mannequin.

Talk to Luna or Wendy to buy lunch box or honey milk. Once you purchase over 400 or 800 a girl will appear in truck.

For Short Wendy you have to do a quest in Evergreen College.

Tall Wendy is behind locked door but no clues are available in game yet.